Check correct bit for PCI range prefetchable attribute.

This seems to have been wrong the whole time.

Test: vmbase_example.integration_test
Change-Id: I88ec99392905ad8fdfb998ba8f6247e2ffd8d444
diff --git a/libs/fdtpci/src/lib.rs b/libs/fdtpci/src/lib.rs
index 602f736..bdd904f 100644
--- a/libs/fdtpci/src/lib.rs
+++ b/libs/fdtpci/src/lib.rs
@@ -206,7 +206,7 @@
 impl PciMemoryFlags {
     /// Returns whether this PCI range is prefetchable
     pub fn prefetchable(self) -> bool {
-        self.0 & 0x80000000 != 0
+        self.0 & 0x40000000 != 0
     }
 
     /// Returns the type of this PCI range